Cobalt/Copper-Cocatalyzed Synthesis of Imidazo[1,2-a:3,4-a′]dipyridiniums from 2H-[1,2′-Bipyridin]-2-ones and 2-Bromoacetophenones

Abstract

A cobalt/copper-cocatalyzed facile synthesis of imidazo[1,2-a:3,4-a']dipyridiniums from 2H-[1,2'-bipyridin]-2-ones and 2-bromoacetophenones is presented. This strategy provides an alternative to the imidazo[1,2-a:3,4-a']dipyridinium synthesis by employing readily available substrates and a simple procedure, which would render this method potentially useful in organic synthesis.

A comprehensive overview of directing groups applied in metal-catalysed C–H functionalisation chemistry

“…For instance, two methods for the synthesis of dipyridoimidazolium compounds were reported by Li ( Scheme 116G ). 709 , 710 Despite giving the same product, the two methods are mechanistically very different. While Method A is technically a cascade directed alkynylation/cyclisation (Rh–alkyne complex is obtained via β-carbon elimination from the alcohol-ligated intermediate 707 ), Method B was proposed to involve pyridine alkylation first, followed by enolisation and nucleophilic attack of the enol to the Co-activated pyridone ring, and Cu-mediated oxidation.…”

1,10‐Phenanthroline: A versatile ligand to promote copper‐catalyzed cascade reactions

“…[29][30][31] Furthermore, the same [CuL] can catalyze various reactions, and cover different reaction mechanisms. [32][33][34][35] Thus, the mechanistic role of [CuL] is complicated, and may be elucidated after specific studies. In this review, based on the proposed reaction mechanism of original papers, the influence of [CuL] is discussed.…”

Recent advances on the transition-metal-catalyzed synthesis of imidazopyridines: an updated coverage

“…A facile synthesis with readily available substrates for imidazo[1,2- a ;3,4- a ']dipyridiniums 370 was reported by Li et al, the synthesis was simple and facile involving cobalt/copper co-catalyzed system [186]. This was the only report after first-ever synthesis of this moiety in 1985.…”